<?php


define("DIR",dirname($_SERVER['SCRIPT_FILENAME']));
$file =DIR. '\\open.gif';

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="'.basename($file).'"');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    readfile($file);
    #readfile函数作用读取内容到缓冲
    exit;
}
?>